%I #10 Sep 12 2018 15:08:53
%S 4,8,39,126,482,1712,6277,22700,82580,299648,1088499,3952186,14352786,
%T 52119040,189266297,687294648,2495834292,9063317432,32912374319,
%U 119517358582,434013128786,1576067091632,5723300581661,20783486354532
%N Number of 3 X n binary arrays with top left element equal to 1 and no two ones adjacent horizontally or antidiagonally.
%H R. H. Hardin, <a href="/A228755/b228755.txt">Table of n, a(n) for n = 1..210</a>
%F Empirical: a(n) = 2*a(n-1) + 6*a(n-2) - a(n-4).
%F Empirical g.f.: x*(2 - x)*(2 + x) / (1 - 2*x - 6*x^2 + x^4). - _Colin Barker_, Sep 12 2018
%e Some solutions for n=4:
%e ..1..0..0..0....1..0..1..0....1..0..0..1....1..0..0..0....1..0..1..0
%e ..1..0..1..0....0..0..0..0....0..0..0..0....0..0..0..1....0..0..0..1
%e ..0..0..0..0....0..1..0..1....0..1..0..1....0..1..0..0....1..0..0..1
%Y Row 3 of A228754.
%K nonn
%O 1,1
%A _R. H. Hardin_, Sep 02 2013